my knee is knackered

My left knee has been giving me jip for the last 2 or 3 months, so I thought it was about time someone took a look at it. Apart from the usual aches and pains I generally have, and the loud creaking noises I'm used to hearing from my joints, I've been having a sharp pain when running, and sometimes when walking. I've also had a vague feeling of fragility in the knee when cycling, as well as some numbness.

So, I made an appointment to see a physio at the Sports Injury Clinic in the hope that they might do a bit of manipulation / stretching / pulling about (or whatever physios do) and make the pain go away. They did indeed do a bit of pulling about, and apparently the ligaments are fine. They pointed out that the muscles in my right leg are rather larger than in the left (I knew that already), at that I need an arthroscopy to repair the worn cartilage that has been causing the pain in my left knee. So, I'm to be referred to the NHS for keyhole surgery. How annoying.